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Wednesday, September 23, 2015

100MHz frequency counter with LCD display

Update November 26, 2015:
I made a full project with preamp/signal conditioning and power supply with soft on/of switch. It is published here.

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This is the same as the previous frequency counter but the output is on the 16x2 LCD display.
For more details about how it work look here: http://diyfan.blogspot.bg/2015/08/100mhz-frequency-counter.html

Bellow are pictures and short video, showing the frequency counter in action. As my oscilloscope is with only 70Mhz bandwidth, the 110+ MHz signal looks like sinusoidal, but it is probably not.
I generate the test signal with SN74HC00N connected in this way:

This is simple ferrite bead for limiting the interference between two parts of the circuit. If I recall correctly it was 120Ohm at 100MHz. I am not sure how critical it is as there is also decoupling capacitor near both IC's supply pins, so it should work fine with piece of wire instead the ferrite bead.